When using chemical solutions for pressure washing concrete surfaces, it’s essential to follow label instructions closely so that you don’t damage your concrete with too much exposure time or concentration of active ingredients (such as acid).
It depends on the type of chemical solution that you are using.
There are two types of concrete cleaning chemicals: alkaline and acidic cleaners. Both types of cleaners are used for different purposes, but they both have unique characteristics that can affect how long they should stay on the surface being cleaned.
Alkaline cleaners are often used on filthy concrete or to remove stains or mildew from concrete surfaces. These solutions typically contain ingredients such as bleach, ammonia, and detergent, which all affect the surface being cleaned. For example, ammonia may cause pitting if left too long on a surface, while bleach can cause discoloration if not rinsed off quickly enough.
Acidic cleaners often clean tough stains from concrete surfaces, such as oil stains. These chemicals typically contain hydrochloric acid or muriatic acid that will burn through most tough stains but also cause damage to your skin if you come into contact with them.
It depends on what you’re cleaning and how much pressure washer spray your concrete has been exposed to.
For example, if you’ve power-washed your driveway and it’s covered in dirt and oil stains, the chemicals from the cleaner may need a longer time to penetrate and clean the concrete surface.
In general, though, here are some guidelines for when you should rinse:
If you’re using a solid alkaline cleaner (such as Concrete Cleaner), wait until the material stops fizzing before rinsing. This is usually about 10 minutes. If you don’t see any fizzing, rinse immediately after applying the product.
Use warm water when rinsing because cold water can cause more damage to concrete than warm or hot water does — which means that colder temperatures could add extra time before a concrete surface dries out completely.
If there are still spots on your driveway after rinsing, try scrubbing them with a stiff brush before applying another cleaner coat. The brush will help remove stubborn stains that might have been missed during previous cleaner applications.